The present invention relates to computer networks in general, and in particular to load balancing client requests among redundant network servers in different geographical locations.
In computer networks, such as the Internet, preventing a server from becoming overloaded with requests from clients may be accomplished by providing several servers having redundant capabilities and managing the distribution of client requests among the servers through a process known as xe2x80x9cload balancing.xe2x80x9d
In one early implementation of load balancing, a Domain Naming System (DNS) server connected to the Internet is configured to maintain several IP addresses for a single domain name, with each address corresponding to one of several servers having redundant capabilities. The DNS server receives a request for address translation and responds by returning the list of server addresses from which the client chooses one address at random to connect to. Alternatively, the DNS server returns a single address chosen either at random or in a round-robin fashion, or actively monitors each of the servers and returns a single address based on server load and availability.
More recently, a device known as a xe2x80x9cload balancer,xe2x80x9d such as the Web Server Director, commercially available from the Applicant/assignee, has been used to balance server loads as follows. The load balancer is provided as a gateway to several redundant servers typically situated in a single geographical location and referred to as a xe2x80x9cserver farmxe2x80x9d or xe2x80x9cserver cluster.xe2x80x9d DNS servers store the IP address of the load balancer rather than the addresses of the servers to which the load balancer is connected. The load balancer""s address is referred to as a xe2x80x9cvirtual IP addressxe2x80x9d in that it masks the addresses of the servers to which it is connected. Client requests are addressed to the virtual IP address of the load balancer which then sends the request to a server based on server load and availability or using other known techniques.
Just as redundant servers in combination with a load balancer may be used to prevent server overload, redundant server farms may be used to reroute client requests received at a first load balancer/server farm to a second load balancer/server farm where none of the servers in the first server firm are available to tend to the request. One rerouting method currently being used involves sending an HTTP redirect message from the first load balancer/server farm to the client instructing the client to reroute the request to the second load balancer/server farm indicated in the redirect message. This method of load balancing is disadvantageous in that it can only be employed in response to HTTP requests, and not for other types of requests such as FTP requests. Another rerouting method involves configuring the first load balancer to act as a DNS server. Upon receiving a DNS request, the first load balancer simply returns the virtual IP address of the second load balancer. This method of load balancing is disadvantageous in that it can only be employed in response to DNS requests where there is no guarantee that the request will come to the first load balancer since the request does not come directly from the client, and where subsequent requests to intermediate DNS servers may result in a previously cached response being returned with a virtual IP address of a load balancer that is no longer available.
Where redundant server farms are situated in more than one geographical location, the geographical location of a client may be considered when determining the load balancer to which the client""s requests should be routed, in addition to employing conventional load balancing techniques. However, routing client requests to the geographically nearest server, load balancer, or server farm might not necessarily provide the client with the best service if, for example, routing the request to a geographically more distant location would otherwise result in reduced latency, fewer hops, or provide more processing capacity at the server.
The present invention seeks to provide novel apparatus and methods for load balancing client requests among redundant network servers and server farms in different geographical locations which overcome the known disadvantages of the prior art as discussed above.
There is thus provided in accordance with a preferred embodiment of the present invention a method for load balancing requests on a network, the method including receiving a request from a requestor having a requestor network address at a first load balancer having a first load balancer network address, the request having a source address indicating the requestor network address and a destination address indicating the first load balancer network address, forwarding the request from the first load balancer to a second load balancer at a triangulation network address, the request source address indicating the requestor network address and the destination address indicating the triangulation network address, the triangulation network address being associated with the first load balancer network address, and sending a response from the second load balancer to the requester at the requestor network address, the response having a source address indicating the first load balancer network address associated with the triangulation network address and a destination address indicating the first requestor network address.
Further in accordance with a preferred embodiment of the present invention the method includes maintaining the association between the triangulation network address and the first load balancer network address at either of the load balancers.
Still her in accordance with a preferred embodiment of the present invention the method includes maintaining the association between the triangulation network address and the first load balancer network address at the second load balancer, and communicating the association to the first load balancer.
Additionally in accordance with a preferred embodiment of the present invention the method includes directing the request from the second load balancer to a server in communication with the second load balancer, composing the response at the server, and providing the response to the second load balancer.
There is also provided in accordance with a preferred embodiment of the present invention a method for load balancing requests on a network, the method including determining the network proximity of a requestor with respect to each of at least two load balancers, designating a closest one of the load balancers by ranking the load balancers by network proximity, and directing requests from the requestor to the closest load balancer.
Further in accordance with a preferred embodiment of the present invention the method includes directing requests from any source having a subnet that is the same as the subnet of the requester to the closest load balancer.
Still further in accordance with a preferred embodiment of the present invention the method includes monitoring the current load of each of the load balancers, and performing the directing step the current load of the closest load balancer is less than the curt load o every other of the load balancers.
Additionally in accordance with a preferred embodiment of the present invention the determining step includes periodically determining.
Moreover in accordance with a preferred embodiment of the present invention the determining step includes determining at at least one fixed time.
Further in accordance with a preferred embodiment of the present invention the determining step includes polling the requestor to yield at least two attributes selected from the group consisting of latency, relative TTL, and number of hops to requestor.
Still further in accordance with a preferred embodiment of the present invention the determining step includes polling the requestor using at least two polling methods selected from the group consisting of: pinging, sending a TCP ACK message to, the requestor""s source address and port, sending a TCP ACK message to the requestor""s source address and port 80, and sending a UDP request to a sufficiently high port number as to elicit an xe2x80x9cICMP port unreachablexe2x80x9d reply.
Additionally in accordance with a preferred embodiment of the present invention the designating step includes designating a closest one of the load balancers by ranking the load balancers by network proximity and either of current load and available capacity.
There is also provided in accordance with a preferred embodiment of the present invention a method for determining network proximity, the method including sending from each of at least two servers a UDP request having a starting TTL value to a client at a sufficiently high port number as to elicit an xe2x80x9cICMP port unreachablexe2x80x9d reply message to at least one determining one of the servers indicating the UDP request""s TTL value on arrival at the client, determining a number of hops from each of the servers to the client by subtract the starting TTL value from the TTL value on arrival for each of the servers, and determining which of the servers has fewer hops of the client, and designating the server having fewer hops as being closer to the client than the other of the servers.
There is additionally provided in accordance with a preferred embodiment of the present invention a network load balancing system including a network, a first load balancer connected to the network and having a first load balancer network address, a second load balancer connected to the network and having a triangulation network address, the triangulation network address being associated with the first load balancer network address, and a requestor connected to the network and having a requestor network address, where the requestor is operative to send a request via the network to the first load balancer, the request having a source address indicating the requestor network address and a destination address indicating the first load balancer network address, the first load balancer is operative to forward the request to the second load balancer at the triangulation network address, the request source address indicating the requestor network address and the destination address indicating the triangulation network address, and the second load balancer is operative to send a response to the requestor at the requester network address, the response having a source address indicating the first load balancer network address associated with the triangulation network address and a destination address indicating the first requestor network address.
Further in accordance with a preferred embodiment of the present invention either of the load balancers is operative to maintain a table of the association between the triangulation network address and the first load balancer network address.
Still further in accordance with a preferred embodiment of the present invention the second load balancer is operative to maintain a table of the association between the triangulation network address and the first load bar network address and communicate the association to the first load balancer.
Additionally in accordance with a preferred embodiment of the present invention the system further includes a server in communication with the second load balancer, where the second load balancer is operative to direct the request from the second load balancer to the server, and the server is operative to compose the response and provide the response to the second load balancer.
There is also provided in accordance with a preferred embodiment of the present invention a network load balancing system including a network, at least two load balancers connected to the network, and a requestor connected to the network, where each of the at least two load balancers is operative to determine the network proximity of the requestor, and at least one of the load balancers is operative to designate a closest one of the load balancers by ranking the load balancers by network proximity and direct requests from either of the requester and a subnet of the requester to the closest load balancer.
Further in accordance with a preferred embodiment of the present invention the load balancers are operative to poll the requester to yield at least two attributes selected from the group consisting of latency, relative TTL, and number of hops to requester.
Still further in accordance with a preferred embodiment of the present invention the load balancers are operative to poll the requestor using at least two polling methods selected from the group consisting of: pinging, sending a TCP ACK message to the requestor""s source address and port, sending a TCP ACK message to the requestor""s source address and port 80, and sending a UDP request to a sufficiently high port number as to elicit an xe2x80x9cICMP port unreachablexe2x80x9d reply.
Additionally in accordance with a preferred embodiment of the present invention at least one of the load balancers is operative to designate the closest one of the load balancers by ranking the load balancers by network proximity and either of current load and available capacity.
It is noted that throughout the specification and claims the term xe2x80x9cnetwork proximityxe2x80x9d refers to the quality of the relationship between a client and a first server or server farm as compared with the relationship between the client and a second server or server farm when collectively considering multiple measurable factors such as latency, hops, and server processing capacity.
There is further provided in accordance with a preferred embodiment of the present invention a method for managing a computer network connected to the Internet through a plurality of routes or Internet Service Providers, includes the steps of: sending polling requests through a plurality of ISPs from a computer network to a remote server computer, receiving replies from the remote server computer corresponding to the polling requests, and measuring proximities of the remote server computer to the computer network based on the received replies.
Further in accordance with a preferred embodiment of the present invention, the plurality of ISPs assign respective IP addresses to the computer network, and the sending step designates a source IP address for each polling request corresponding to the ISP through which the polling request is sent.
Still further in accordance with a preferred embodiment of the present invention the polling requests may be TCP/IP requests, UDP requests, or ping requests.
Additionally in accordance with a preferred embodiment of the present invention, the measuring step measures proximities based on the number of hops undergone by the received replies in travelling from the remote server to the computer network. Preferably the measuring step measures proximities based on the latency, relative TTL, and number of hops of the received replies in travelling from the remote server to the computer network.
Additionally or alternatively the measuring step may measure proximities based on the number of hops undergone by the received replies in travelling a round trip from the computer network to the remote server and back to the computer network, based on the TTL of the received replies in travelling a round trip from the computer network to the remote server and back from the remote server to the computer network, based on the latency of,the received replies in travelling from the remote server to the computer network or based on the latency of the received replies in travelling a round trip from the computer network to the remote server and back from the remote server to the computer network.
Further in accordance with a preferred embodiment of the present invention the method for managing a computer network connected to the Internet through a plurality of network connection, such as different Internet Service Providers, may also include the steps of rating the plurality of ISPs based on the measured proximities, and entering the ratings in a proximity table within a table entry indexed by an address related to the remote server computer.
Preferably the rating step also determines the best three choices for ISPs based on the measured proximities.
Additionally or alternatively the address related to the remote server computer is a subnet IP address of the remote server computer.
There is also provided in accordance with yet another preferred embodiment of the present a method for managing a computer network connected to the Internet through a plurality of ISPs, includes the steps of: receiving a request from a client within a computer network directed to a remote server computer, looking up a table entry within a proximity table indexed by an address related to the remote server computer, the tables entries of the proximity table containing ratings for a plurality of ISPs, and selecting one of the plurality of ISPs through which to route the client request, based on the ratings within the table entry looked up in the proximity table.
Further in accordance with a preferred embodiment of the present invention, the related to the remote server is a subnet IP address of the remote server.
Still further in accordance with a preferred embodiment of the present invention, the table entries contain the best three choices for ISPs through which to route the client request, and wherein the selecting step selects the best ISP, from among the best three choices for ISPs, that is available and not overloaded.
Additionally in accordance with a preferred embodiment of the present invention, the selecting step determines whether or not an ISP is overloaded based upon a user-configurable load threshold. Furthermore, the selecting step may also select an ISP based on current load, in the event that all three of the best three choices for ISP are unavailable or overloaded.
Further in accordance with a preferred embodiment of the present invention the plurality of ISPs assign respective IP addresses to the computer network, and wherein the method further comprises the step of setting the source IP address of the client request corresponding to the selected ISP.
Moreover in accordance with a preferred embodiment of the present invention the method also includes the step of routing the client request through the selected ISP. Preferably the plurality of ISPs assign respective IP addresses to the computer network, and the routing step designates a source IP address for the client request corresponding to the selected ISP.
The computer network may further be a private network, visible externally through a network address translation. Preferably the method may also include the steps of receiving a response from the remote server directed to the source IP address designated for the client request, and translating the source IP address designated for the client address to the IP address for the client within the private network.
There is further provided in accordance with yet another preferred embodiment of the present invention a network management system for managing a computer network connected to the Internet through a plurality of ISPs, including a network controller sending polling requests through a plurality of ISPs from a computer network to a remote server computer, and receiving replies from the remote server computer corresponding to the polling requests, and a proximity analyzer measuring proximities of the remote server computer to the computer network based on the replies.
Further in accordance with a preferred embodiment of the present invention the plural of ISPs assign respective IP addresses to the computer network, and the network controller designates a source IP address for each polling request corresponding to the ISP through which the polling request is sent.
Furthermore the polling requests may be TCP/IP requests, UDP requests, or ping requests.
Additionally in accordance with a preferred embodiment of the present invention the proximity analyzer measures proximities based on the number of hops undergone by the received replies in traveling from the remote server to the computer network. The proximity analyzer may measure proximities based on the latency, relative TTL, and number of hops of the received replies in traveling from the remote server to the computer network.
Moreover in accordance with a preferred embodiment of the present invention the proximity analyzer rates the plurality of ISPs based on the measured proxies. The system may further include a data manager entering the ratings in a proximity table within a table entry indexed by an address related to the remote server computer. Preferably the proximity analyzer determines the best three choices for ISPs based on the measured proximities.
Additionally in accordance with a preferred embodiment of the present invention, the address related to the remote server computer is a subnet IP address of the remote server computer.
There is also provided in accordance with another preferred embodiment of the present invention, a network management system for managing a computer network connected to the Internet through a plurality of ISPs, including a network controller receiving a client request from within a computer network directed to a remote server computer, and selecting one of a plurality of ISPs through which to route the client request, and a data manager looking up a table entry within a proximity table indexed by an address related to the remote server computer, the tables entries of the proximity table containing ratings for a plurality of ISPs. The network controller may also select one of the plurality of ISP based on the rating within the table entry looked up in the proximity table.
Further in accordance with a preferred embodiment of the present invention the address related to the remote server is a subnet IP address of the remote server.
Still further in accordance with a preferred embodiment of the present invention, the table entries contain the best three choices for ISPs through which to route the client request, and the network controller selects the best ISP, from among the best three choices for ISPs, that is available and not overloaded. Preferably the network controller also determines whether or not an ISP is overloaded based upon a user-configurable load threshold.
Additionally in accordance with a preferred embodiment of the present invention, the network controller selects an ISP based on current load, in the event that all three of the best three choices for ISP are unavailable or overloaded The plurality of ISPs may assign respective IP addresses to the computer network, the network controller designates a source IP address for the client request corresponding to the selected ISP.
Moreover in accordance with a preferred embodiment of the present invention, the network controller routes the client request through the selected ISP. Preferably the computer network is a private network, visible externally through a network address translation, and the network controller receives a response from the remote server directed to the source IP address designated for the client request, the system further comprising a network address translator translating the source IP address designated for the client address to the IP address for the client within the private network.
There is also provided in accordance with yet another preferred embodiment of the present invention a method for managing a computer network connected to the Internet through a plurality of ISPs, including the steps of receiving a DNS resolution query from a remote computer for a domain name within a computer network, sending polling requests through a plurality of ISPs from the computer network to the remote computer, receiving replies from the remote computer corresponding to the polling requests, and measuring proximities of the remote computer to the computer network based on the replies.
Further in accordance with a preferred embodiment of the present invention the plurality of ISPs assign respective IP addresses to the computer network, and the sending step designates a source IP address for each polling request corresponding to the ISP through which the polling request is sent.
Still further in accordance with a preferred embodiment of the present invention the polling requests may be TCP/IP requests, UDP requests, or ping requests.
Additionally in accordance with a preferred embodiment of the present invention, the measuring step measures proximities based on the number of hops undergone by the received replies in travelling from the remote server to the computer network.
Further in accordance with a preferred embodiment of the present invention the proximity analyzer measures proximities based on the number of hops undergone by the received replies in traveling a round trip from the computer network to the remote server and back to the computer network.
Alternatively the proximity analyzer measures proximities based on the TTL of the received replies in travelling a round trip from the computer network to the remote server and back to the computer network, on the latency of the received replies in travelling from the remote server to the computer network, or on the latency of the received replies in travelling a round trip from the computer network to the remote server and back to the computer network.
Moreover in accordance with a preferred embodiment of the present invention, the measuring step may also measure proximities based on the latency, relative TTL, and number of hops of the received replies in travelling from the remote server to the computer network.
The method may further include the steps of: rating the plurality of ISPs based on the measured proximities, and entering the ratings in a proximity table within a table entry indexed by an address related to the remote server computer. Preferably the rating step determines the best three choices for ISPs based on the measured proximities.
Additionally or alternatively the address related to the remote server computer is a subnet IP address of the remote server computer.
There is further provided in accordance with yet another preferred embodiment of the present invention a method for managing a computer network connected to the Internet through a plurality of ISPs, which includes the steps of: receiving a DNS resolution query from a remote computer for a domain name within a computer network, looking up a table entry within a proximity table indexed by an address related to the remote computer, the tables entries of the proximity table containing ratings for a plurality of ISPs, selecting one of the plurality of ISPs, based on the ratings within the table entry looked up in the proximity table, and responding to the DNS resolution query with an IP address associated with the selected one of the plurality of ISPs.
Further in accordance with a preferred embodiment of the present invention the address related to the remote computer is a subnet IP address of the remote computer.
Still further in accordance with a preferred embodiment of the present invention the table entries contain the best three choices for ISPs through which to connect to the remote computer from within the computer network, and the selecting step selects the best ISP, from among the best three choices for ISPs, that is available and not overloaded. Preferably the selecting step determines whether or not an ISP is overloaded based upon a user-configurable load threshold.
Additionally in accordance with a preferred embodiment of the present invention, the selecting step selects an ISP based on current load, in the event that all three of the best three choices for ISP are unavailable or overloaded.
Further in accordance with a preferred embodiment of the present invention the plurality of ISPs assign respective IP addresses to the computer network and wherein said network controller sets the source IP address of the client request corresponding to the selected ISP.
Moreover in accordance with a preferred embodiment of the present invention, the plurality of ISPs assign respective IP addresses to the computer network, and the responding step designates an IP address corresponding to the selected ISP. Preferably the computer network is a private network, visible externally through a network address translation.
Still further in accordance with a preferred embodiment of the present invention the responding step designates an IP address of an internal server that supports the domain name in the DNS query.
The method may further include the steps of: receiving a request having a destination IP address corresponding to the selected ISP, and translating the destination IP address to an IP address within the private network.
There is also provided in accordance with yet another preferred embodiment of the present invention a network management system for managing a computer network connected to the Internet through a plurality of ISPs, including a network controller receiving a DNS resolution query from a remote computer for a domain name within a computer network, sending polling requests through a plurality of ISPs from the computer network to the remote computer, and receiving replies from the remote computer corresponding to the polling requests, and a proximity analyzer measuring proximities of the remote computer to the computer network via the plurality of ISPs, based on the replies.
Further in accordance with a preferred embodiment of the present invention, the plurality of ISPs assign respective IP addresses to the computer network, and the network controller designates a source IP address ISP each polling request corresponding to the ISP through which the polling request is sent.
Still further in accordance with a preferred embodiment of the present invention, the polling requests are TCP/IP requests, UDP requests, or ping requests.
Additionally in accordance with a preferred embodiment of the present invention the proximity analyzer measures proximities based on the number of hops undergone by the received replies in travelling from the remote server to the computer network.
Moreover in accordance with a preferred embodiment of the present invention, the proximity analyzer measures proximities based on the latency, relative TTL, and number of hops of the received replies in travelling from the remote server to the computer network.
Still further in accordance with a preferred embodiment of the present invention, the proximity analyzer rates the plurality of ISPs based on the measured proximities, and enters the ratings in a proximity table within a table entry indexed by an address related to the remote server computer. Preferably the proximity analyzer determines the best three choices for ISPs based on the measured proximities.
Additionally in accordance with a preferred embodiment of the present invention, the address related to the remote server computer is a subnet IP address of the remote server computer.
There is further provided in accordance with yet another preferred embodiment of the present invention, a network management system for managing a computer network connected to the Internet through a plurality of ISPs, including a network controller receiving a DNS resolution query from a remote computer for a domain name within a computer network, selecting one of a plurality of ISPs, and responding to the DNS resolution query with an IP address associated with the selected ISP, and a data manager looking up a table entry within a proximity table indexed by an address related to the remote computer, the tables entries of the proximity table containing ratings for the plurality of ISPs. The network controller may also select an ISP based on ratings within the table entry looked up in the proximity table.
Further in accordance with a preferred embodiment of the present invention, the address related to the remote computer is a subnet IP address of the remote computer.
Still further in accordance with a preferred embodiment of the present invention, the table entries contain the best three choices for ISPs through which to connect to the remote computer from within the computer network, and the network controller selects the best ISP, from among the best three choices for ISPs, that is available and not overloaded. Preferably, the network controller determines whether or not an ISP is overloaded based upon a user-configurable load threshold.
Additionally in accordance with a preferred embodiment of the present invention the network controller selects an ISP based on current load, in the event that all three of the best three choices for ISP are unavailable or overloaded.
Moreover in accordance with a preferred embodiment of the present invention, the plurality of ISPs assign respective IP addresses to the computer network, and wherein said network controller designates an IP address corresponding to the selected ISP. Preferably the computer network is a private network, visible externally through a network address translation.
Still further in accordance with a preferred embodiment of the present invention the network controller designates an IP address of an internal server that supports the domain name in the DNS query.
Additionally or alternatively the network controller receives a request having a destination IP address corresponding to the selected ISP; the system further comprising a network address translator translating the destination IP address to an IP address within the private network.
There is thus provided in accordance with yet another preferred embodiment of the present invention a routing system for routing data via a network from a first node to a second node, and wherein the network having a plurality of available routes from the first node to the second node, and the system also includes a route selector operable to select one of the routes for sending data between the first node and second node on the basis of content information of the data, an obtained quality level of the routes and proximity information.
There is further provided in accordance with a further preferred embodiment of the present invention a routing system for routing data via a network from a of node to a second node, and wherein the network having a plurality of available routes from the first node to the second node, and the system also includes a route selector operable to select one of the routes for sending data between the first node and second node on the basis of costing information of said routes.
Further in accordance with a preferred embodiment of the present invention the route selector is operable to select one of the routes for sending data between the first node and second node additionally on the basis of costing information of the routes.
Still further in accordance with a preferred embodiment of the present invention the route selector is operable to perform optimization between content information of the data and costing information of the routes, to select a route.
Additionally in accordance with a preferred embodiment of the present invention the route selector is operable to perform optimization additionally on the basis of delay time of the connection, to select a route.
Moreover in accordance with a preferred embodiment of the present invention the route selector is operable to perform optimization additionally on the basis of path quality, to select a route.
Additionally in accordance with a preferred embodiment of the present invention the route selector is operable to perform optimization additionally on the basis of traffic load, to select a route.
Still further in accordance with a preferred embodiment of the present invention the route selector is operable to perform optimization additionally on the basis of delay time of the connection.
Furthermore, a Destinations Table is built to summarize the connection data for each one of a plurality of possible destination nodes. The Destinations Table is built based on previously determined proximities.
Additionally the route selector is operable to configure and use a Decision Parameter Table comprising parameters of the routes. Furthermore, different Decision Parameters are supplied for each respective content type. The Decision Parameter Table also includes at least one of a group of parameter weights comprising; Data packet content; Hops weighting factor, Packet loss factor and Response time factor. It is appreciated that a different Decision Parameters is used for each respective content.
A Decision Function Fcontent is calculated for each path from the first node to the second node, based on said Decision Parameter Table. The Decision Function Fcontent is defined as:
Fcontent=F(Hops weighting factor*Hops count factor; Response weighting factor*Response time factor; Path quality weighting factor*Path quality factor, Packet loss weighting factor*Packet loss factor).
All factors and weights are taken from the Destination Table and the Decision Parameter Table, respectively.
Still further in accordance with a preferred embodiment of the present invention, the above parameters, which are used in the calculation of Fcontent, are normalized for each path.
Still further in accordance with a preferred embodiment of the present invention, all previously defined factors are normalized for each path between the first node and the second node. Preferably the route selector is operable to decide on the path for routing the data packet from the first node to said second node based on said Decision Function.
The network connection may be for the Internet or for different ISPs.
There is further provided in accordance with yet another preferred embodiment of the present invention a method for routing data by a content routing system from a first node to a second node via a network and including the steps of providing a plurality of available routes from the first node to the second node and selecting one of the routes for sending data between the first node and second node on the basis of content information of the data.
There is also provided in accordance with yet another preferred embodiment of the present invention a method for routing data by a content routing system from,a first node to a second node via a network and including the steps of providing a plurality of available routes from the first node to the second node and a route selector selecting one of the routes for sending data between the first node and second node on the basis of costing information of the routes.
Further in accordance with a preferred embodiment of the present invention the method includes selecting one of the routes for sending data between the first node and second node on the basis of costing information of the routes.
Still further in accordance with a preferred embodiment of the present invention the method further includes the step of performing optimization between content information of the data and costing information of the routes.
Moreover in accordance with a preferred embodiment of the present invention, including the step of performing optimization additional on the basis of delay time of the connection or on the basis of path quality of the connection, or on the basis of packet loss of the path, or on a combination of any of these parameters. Further in accordance with a preferred embodiment of the present invention the available routes possess a path quality factor Qi. The path quality factor Qi is defined as being a function of the traffic load, packet loss, and link pricing. Additionally, the path quality factor Qis dependent on the content of the data packet.
Still further in accordance with a preferred embodiment of the present invention the path quality factor Qi is checked periodically.
There is further provided in accordance with a preferred embodiment of the present invention a method for calculating a path quality parameter for a network path between a first node and a second node, including the step of checking the availability of the path, the cost of the path connection, and the data packet loss rate of the path.